(reduce #(concat %1 (if (> %2 6) [ :foo %2] [%2])) [] '(3 4 5 8 4 2)) Note that I am not a programmer and do not know much about writing code, however the above snippet in my view can achieve the result you desired. I invite comments on the above.
Regards, Emeka On Thu, Apr 23, 2009 at 10:52 AM, Christophe Grand <christo...@cgrand.net>wrote: > > *Warning this message contains mutable state and may hurt functional > sensibilities.* > > Ugly hack: > > (defn my-split-with [pred coll] > (let [s (atom coll) > p #(when-let [r (pred %)] (swap! s rest) r)] > [(take-while p coll) (drop-while pred (lazy-seq @s))])) > > Now it works ;-) > > Laurent PETIT a écrit : > > This is a general problem with function (split-with) (and derivatives > > such as partition-by ...), > > > > This should certainly deserve a mention in their respective > > docstrings, I think. Because the docstring speak about lazyness, but > > not the kind of lazyness that can avoid Out of Memory in corner cases. > > > > Rich, if you agree with that, would you me to issue a patch on google > group ? > > > > 2009/4/23 Christophe Grand <christo...@cgrand.net>: > > > >> Laurent PETIT a écrit : > >> > >>> Hi Meikel, > >>> > >>> It seems to me that your version is the only safe one so far, that > >>> would succesfully indefinitely return values with this test: > >>> > >>> (dorun (mystery-function true? :foo (repeat true))) > >>> > >>> Mine, a new version of mine I'll never bother to publish, and > >>> Christophe's all retain head. > >>> To explain on Christophe's one for example: > >>> > >>> It uses (split-with) which, in case pred always match coll elements, > >>> will retain the head of coll in etc, while eating more and more > >>> elements of coll via running on run : > >>> 1:21 user=> (defn mystery-function [pred coll] > >>> (lazy-seq > >>> (when (seq coll) > >>> (let [[run etc] (split-with pred coll)] > >>> (if (seq run) > >>> (concat run (cons :foo (mystery-function pred etc))) > >>> (cons (first coll) (mystery-function pred (rest coll)))))))) > >>> 1:22 user=> (dorun (mystery-function true? (repeat true))) > >>> java.lang.OutOfMemoryError: GC overhead limit exceeded (repl-1:22) > >>> > >>> > >> Nice catch! > >> > >> > >> -- > >> Professional: http://cgrand.net/ (fr) > >> On Clojure: http://clj-me.blogspot.com/ (en) > >> > >> > >> > >> > > > > > > > > > > > > -- > Professional: http://cgrand.net/ (fr) > On Clojure: http://clj-me.blogspot.com/ (en) > > > > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~----------~----~----~----~------~----~------~--~---
